1. Field of the Invention
The invention relates to a CSP (Chip Size Package) type semiconductor device and a method of manufacturing the same, in particular, a semiconductor device and a method of manufacturing the same in which a supporting substrate is attached to a surface of a semiconductor substrate with an adhesive layer being interposed therebetween.
2. Description of the Related Art
A CSP technique keeps an unchallengeable status as a three-dimensional packaging technique while a portable device or the like is designed to be more lightened, thinned and shortened. The CSP means a small package of which the outer dimensions are almost the same as those of a semiconductor die.
Among CSP type semiconductor devices, a brief description will be given about a semiconductor device having a photoelectric integrated circuit as a CSP, that includes a light receiving element such as an image sensor, a control circuit controlling an output of the image sensor, and so on, referring to FIGS. 6A and 6B. FIG. 6A is a perspective view of the semiconductor device on the front surface side, and FIG. 6B is a perspective view of the semiconductor device on the back surface side.
The semiconductor device 101 is formed so that a semiconductor die 104 is sealed between first and second glass substrates 102, 103 with epoxy resins 105a, 105b being interposed therebetween. A plurality of ball-shaped conductive terminals 106 are disposed in a grid pattern on one surface of the second glass substrate 103, i.e., on the back surface of the semiconductor device 101.
These conductive terminals 106 are connected to the semiconductor die 104 through second wirings 110. Aluminum wirings led from inside the semiconductor die 104 are connected to the plurality of second wirings 110 respectively, achieving electric connection between the conductive terminals 106 and the semiconductor die 104.
A cross-sectional structure of the semiconductor device 101 will be described in detail referring to FIG. 7. FIG. 7 shows the cross-sectional view of the semiconductor device 101 completed by dividing each of the semiconductor dies 104 along dicing lines.
A first wiring 107 is provided on an insulation film 108 disposed on the front surface of the semiconductor die 104 on which a light receiving element such as an image sensor or the like is formed, being connected to the image sensor or the like. This semiconductor die 104 is attached to the first glass substrate 102 with a resin 105a. The back surface of this semiconductor die 104 is attached to the second glass substrate 103 with a resin 105b. 
One end of the first wiring 107 is connected to the second wiring 110. This second wiring 110 is extended from one end of the first wiring 107 to the front surface of the second glass substrate 103. The ball-shaped conductive terminals 106 are formed on the second wiring 110 extended on the second glass substrate 103, forming the CSP type semiconductor device 101.
A CSP type semiconductor device having a light receiving element such as an image sensor or the like is disclosed in many documents, and also in the Japanese Patent Application Publication No. 2002-512436.
The Japanese Patent Application Publication No. 2002-512436 discloses attaching the semiconductor die 104 and the first glass substrate 102 and attaching the semiconductor die 104 and the second glass substrate 103 with an epoxy resin using an attaching apparatus. This document discloses this attaching apparatus as having a system that rotates while pressing the semiconductor die 104, the glass substrate 102 or 103 and an epoxy resin so as to realize an optimum attachment state with a uniformly spread epoxy resin.
On the other hand, in order to prevent decrease in the amount of light entering the light receiving element due to a passivation silicon nitride film that is formed on the upper surface of the light receiving element and absorbs light entering the semiconductor die 104, the passivation silicon nitride film on the region of the light receiving element need be removed. Therefore, a recess portion is formed on the region of the light receiving element, being lower than the surrounding control circuit region.
With this structure, when an adhesive layer for attaching the semiconductor die 104 and the glass substrate 102 or the like is applied by high speed rotation, there may occur a problem that the recess portion is filled with an epoxy resin as an adhesive material with bubbles. From the aspect of the yield and reliability, it is important to prevent bubbles from being mixed in the adhesive layer that fills the recess portion formed on the region of the light receiving element.